Agronomic constraints limit the climate change mitigation potential of winter cover crops in Europe

Cover cropping is widely promoted as a promising practice for soil carbon sequestration in agricultural land. Yet, estimates for its greenhouse gas mitigation potential often overlook key factors limiting the feasibility of upscaling. As a result, current potentials may overestimate the climate change mitigation capacity of cover cropping. To support more realistic assessments, we developed and tested a framework to quantify the potential additional adoption of winter cover crops in three European countries: the Netherlands, Germany, and Spain. We addressed two key questions: (1) What is the potential for additional cover cropping based on current adoption? (2) What biophysical and socioeconomic factors influence further adoption? Through an online survey of 321 farmers, we gathered data on crop rotations, current cover crop use, and agronomic constraints. The results show that most farmers already cultivate winter cover crops on at least part of their land in Germany (89 % of farmers) and the Netherlands (97 % of farmers), with only 11 % of arable land in Germany and 25 % in the Netherlands still available for further cover crop cultivation; most arable land is already covered in winter. Soil type, late harvests, and weather conditions were significant biophysical constraints to expansion in both countries. In Spain, no cover crop adoption was detected in rainfed arable systems, largely due to water scarcity. The farmers mentioned benefits such as improved soil health and reduced nitrate leaching as key drivers of adoption. We conclude that the potential for additional carbon sequestration through cover cropping is limited. Taking into account agronomic factors is needed to bring greater realism to carbon sequestration potentials of soil management practices.